Fibrosarcomatous change in dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans which included fibrosarcomatous areas is rarely seen. In one case, we estimated the proportion of area of dermatofibrosarcoma protuberans and fibrosarcomatous area. We also estimated mitotic rate, cellularity, and cytologic anaplasia in these areas. Histologically, the fibrosarcoma area showed a cellularity, mitotic figures, and cytologic anaplasia exceed those seen in the dermatofibrosarcoma protuberans area. The proportion of the fibrosarcoma area was 89%. In both dermatofibrosarcoma protuberans and fibrosarcoma areas, giant cells, necrosis and haemorrhagea was absent. In conclusion, we believe that the dermatofibrosarcoma protuberans which included fibrosarcomatous areas may be an intermediate type between dermatofibrosarcoma protuberans and fibrosarcoma.